There are available today many different liquid-dispensing apparatuses for dispensing a liquid in the form of a jet, spray or aerosol. Some typical apparatuses are aerosol cannisters which find wide application in the home and industry; lever operated devices, such as oil cans, which effectively squirt the liquid; paint-spray guns which are permanently connected to a source of compressed air during operation; sprays, such as garden sprays, in which the space above the liquid is pressurised by means of an integral hand pump, and beverages dispensing devices such as soda siphons in which the liquid is pressurised and sometimes aerated by coupling a cartridge of a compressed gas to a valve on the device to pressurise the contents of the device and then removing and discarding the cartridge before using the device. It has also been proposed to provide a re-fillable aerosol container which is recharged with a liquid under pressure but this necessitates the provision of a relatively large storage tank for the bulk liquid under pressure and complicated valve means for connecting the storage tank to the dispensing apparatus when it is required to re-charge the latter and venting means in the dispensing apparatus to vent the interior of the dispensing apparatus as it is re-charged.
There has long been a need for a relatively cheap, efficient and reliable liquid-dispensing apparatus for use in garages, factories, workshops and the like. There is also a need for such an apparatus which is relatively small and easily maneuverable so that a liquid can be dispensed towards parts where access is difficult; a typical requirement being for apparatus for dispensing a lubricating or penetrating oil on a part in a vehicle, machine or machine tool.
Aerosol cannisters have been used in such applications but they tend to be relatively expensive and wasteful in that it is not always possible to dispense all of the liquid in the cannister before the propellent gas is exhausted. In addition, there is the problem of ensuring that they are used in a safe manner and of their disposal. Apparatus with lever-operated dispensing means are also used in such applications but often they are incapable of dispensing the liquid at sufficient pressure and they lack manoeuvrability; apparatus with integral hand pumps tend to be bulky and the pressure which can be attained by the user tends to be limited; and spray guns permanently connected to a compressed-air line are difficult to maneuver. It is not known whether a device requiring a cartridge of a compressed gas to pressurise its contents has been used in the applications described in the immediately preceding paragraph but it seems doubtful in view of the need always to have available a supply of the relatively expensive cartridges and it is probable that their use has been mainly a domestic one for dispensing drinks.